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(1) Field of the Invention
The present invention relates generally to forms for poured concrete roof and floor decks, and more particularly to an improved form system with attachable segments for on-site custom adjustment of the depth of concrete structural joists that may be integrated into the concrete deck formed by the forms or otherwise used as structural supports.
(2) Background Information
It is well known in the construction industry to utilize expanded plastic material for forms used in the construction of poured concrete walls and the like. In the formation of walls, the expanded plastic forms may either be removed once the concrete has hardened, or left in place to provide thermal and sound insulation to the completed structure.
A relatively recent innovation in the field of expanded plastic forms is disclosed in PCT patent application No. PCT/EP 97/05671, owned by Plastedil S. A. of Switzerland. That application discloses a self-supporting construction element made of expanded plastic material which is extruded with steel studs embedded therein. Each panel is molded with a steel stud imbedded therein during the molding process. The panels may then be cut to a desired length and interconnected to form a floor upon which concrete may be cast. A lath for supporting at least one layer of a covering material is fastened to the reinforcing bar in the panel, the lath providing fire resistant properties to the panel.
While the Plastedil forms provided a new system for forming cast in place concrete decks, the equipment needed to mold the plastic panel with the steel reinforcing bar therein was expensive and complicated. Because of the expense and time involved in creating the panels, the cost of using the system could be prohibitively expensive.
The applicant herein improved on this system by providing a method of manufacturing the form panels which made the production of the components simple and much more cost efficient. This improvement was the subject of applicant""s U.S. Pat. No. 6,272,749, the disclosure of which is incorporated herein by reference thereto.
While the patented method provided less expensive form panels, it was still necessary to mold form panels in a variety of different thicknesses to form decks with joists of different depths to thereby accommodate spans of different lengths. Thus, it was required to stock a variety of different form thicknesses to insure that the appropriate thickness was available for a particular job. In the alternative, a predetermined number of panels of each particular thickness of form would have to be individually ordered and molded for a particular job. These panels typically could not be interchanged with one another at the job site, so it would be necessary to return and re-order panels if the job changed or any of the panels was damaged.
In addition, the existing form system did not provide for additional cross-bracing or other transverse structural strength. Thus, the use of the forms was limited to those jobs that did not require this additional transverse structural strength.
Another problem with prior art forms was the fact that the forms could not be removed once the concrete was poured and hardened, requiring the forms to be left in place. In addition, prior art forms were designed for use solely with an integrated concrete deck, and did not provide for the use of the forms to create joists that could be utilized as separate structural members for a structure.
It is therefore a general object of the present invention to provide an improved form panel system for the creation of poured concrete joists used in the support of decks and roofs.
A further object of the present invention is to provide a system of form panels that may be adjusted on-site for the creation of a variety of joist depths for a particular job.
Yet another object is to provide an improved form system that permits the creation of transverse joists in the deck.
These and other objects will be apparent to those skilled in the art.
The improved form panel system of the present invention includes a basic form panel of expanded polystyrene material having at least one slot formed in the top surface along its length, to divide the panel top surface into piers. A series of top hats are provided for selective attachment to the piers to increase the depth of the slots between piers, and thereby increase the depth of a T-joist formed by hardened concrete poured into the slot and over the top of the panels. The form system thereby creates a concrete deck with integrated concrete joists for supporting the deck. Transverse slots may also be formed by separating top hats along their lengths. This, in turn, creates transverse bracing in the concrete deck for additional strength in the transverse direction. The form panels and top hats may also be used to create separate structural joists with attachment lifts, to permit connection of the joists to a subsequently constructed floor or deck system. The subsequent floor or deck need not necessarily be a concrete deck.